Internal combustion engines are often used to power small equipment such as lawnmowers, tillers, snow throwers, lawn tractors, pressure washers, generators, other outdoor power equipment, etc. The fuel system for these internal combustion engines includes a fuel tank, in which fuel is stored for use. Generally, the volatility of the fuel allows for a portion of the fuel to evaporate and mix with air within the fuel tank. Changes in temperature, such as those between daytime and evening, as well as “sloshing” during use can cause an increase or a decrease in the amount of fuel vapor in the tank as well as an increase or decrease in the pressure within the tank.
The fuel tank cap often includes a fuel vapor filtering element. This filtering element may include an activated carbon bed, which filters the fuel vapor from the air to substantially reduce or eliminate any fuel vapor emissions from the fuel system. Alternatively, filtering elements may be located in areas of the system other than the fuel tank cap (e.g., dedicated carbon canisters within the fuel tank or in-line with the fuel delivery passage). Regardless of where the filtering element is located, these components add cost and complexity to the fuel system in order to control evaporative emissions.
Other systems for controlling fuel vapor utilize a flexible conduit or hose that is in communication with a vapor space of the fuel tank and which delivers fuel vapor to an air cleaner or carburetor system to enable the engine to “burn” evaporative emissions from the fuel tank when the engine is operating. However, these systems suffer from cost and manufacturing complexity issues related to running a substantial length of conduit or flexible between the fuel tank and the air cleaner or carburetor system.